Riesz potentials associated with the composite power function on the space of rectangular matrices. Khekalo, S.P. — 2005 Zapiski Nauchnykh Seminarov POMI
Gauge-equivalent deformations of linear ordinary differential operators with constant coefficients. Khèkalo, S.P. — 2004 Journal of Mathematical Sciences (New York)
Time deformations of powers of the wave operator. Khèkalo, S.P. — 2005 Zapiski Nauchnykh Seminarov POMI